Hf broadband omnidirectional antenna

ABSTRACT

An HF antenna providing high-angle skywave radiation at the lower end of the 2 MHz to 30 MHz band and low-angle skywave radiation at the upper frequencies with substantially gapless coverage in range from 0 to 1,000 miles with pattern characteristics optimized for propagation conditions. It utilizes predominantly horizontal polarization in minimizing ground losses in a log-periodic dipole array with elements lying in two orthogonal vertical planes with the apex substantially at ground level. It is an array with the phase center approximately a quarter-wavelength above ground at the lower frequencies and thereby near-vertical radiation for the short path circuits. Then as the frequency increases from 2 MHz to 6 MHz, the phase center increases from a quarter-wavelength above ground to near a halfwavelength above ground, providing lower angle radiation with omnidirectional characteristics. Antenna input impedance is from 50 ohms unbalanced coax line through an impedance transforming balun to 200 ohms balanced having VSWR with respect to the 50 ohm input line of less than 2.5 to 1. A single supporting tower occupying a near-minimum space volume is employed with phase controlled not only between orthogonal element bays but also between elements in each bay with one quarter phase spacing of elements so as to attain a desired elliptical polarization propagation characteristic.

United States Patent Cory et al.

[54] HF BROADBAND OMNIDIRECTIONAL ANTENNA [72] Inventors: Terry S. Cory;William A. Kennedy,

both of Richardson, Tex.

[73] Assignee: Collins Radio Company, Dallas,

Tex.

[22] Filed: April 26, 1971 [21] Appl.No.: 137,371

[52] US. Cl. ..343/792.5, 343/798, 343/809, 343/89] [51] Int. Cl. ..H0lq11/10 [58] Field of Search.,.343/792.5, 796, 797, 798, 809, 343/878, 89]

[56] References Cited UNITED STATES PATENTS 3,181,161 4/1965 Minerva..343/792.5 3,221,332 ll/l965 Kravis et al ..343/792.5

Primary ExaminerEli Lieberman Attorney-Warren H. Kintzinger and RobertJ. Crawford 1 Aug. 8, 1972 [57] ABSTRACT An HF antenna providinghigh-angle skywave radiation at the lower end of the 2 MHz to 30 MHzband and low-angle skywave radiation at the upper frequencies withsubstantially gapless coverage in range from 0 to 1,000 miles withpattern characteristics optimized for propagation conditions. Itutilizes predominantly horizontal polarization in minimizing groundlosses in a log-periodic dipole array with elements lying in twoorthogonal vertical planes with the apex substantially at ground level.It is an array with the phase center approximately a quarter-wavelengthabove ground at the lower frequencies and thereby near-verticalradiation for the short path circuits. Then as the frequency increasesfrom 2 MHz to 6 MHz, the phase center increases from aquarter-wavelength above ground to near a half-wavelength above ground,providing lower angle radiation with omnidirectional characteristics.Antenna input impedance is from 50 ohms unbalanced coax line through animpedance transforming balun to 200 ohms balanced having VSWR withrespect to the 50 ohm input line of less than 2.5 to l. A singlesupporting tower occupying a near-minimum space volume is employed withphase controlled not only between orthogonal element bays but alsobetween elements in each bay with one quarter phase spacing of elementsso as to attain a desired elliptical polarization propagationcharacteristic.

16 Claims, 20 Drawing Figures PATENTEDMJG 81912 3.683.390

sum 3 or 7 63W) w a;

m [UB1 FIG.3

IN VENTORS TERRY S. CORY WILLIAM A. KENNEDY PATENTED 8 I973 Y 3.683.390

' sum u 0F 7 INVE N TORS TERRY S. CORY WILLIAM A. KENNEDY P'ATENTE'DAUB8'97? I 3.683.390

' SHEET 5 BF 7 FREQUENCY lN MHz FIG.8

IN VE N TORS TERRY 5. CORY WILLIAM A. KENNEDY PATENTEDAUB s 1912 SHEET 60F 7 I ZMHz FIG.9

6 MHz 20 MHz FIG.|3

4 MHz FIG.|O

l2 MHz FIG. I2

30 MHz FIG.I4

INVENTORS ERRY CORY WIL M A. K NEDY ATTORNEY 1 HF BROADBAND()MNTDIREC'IIONAL ANTENNA This invention relates in general to antennasystems and, in particular, to a horizontally polarized,omnidirectional, log-periodic array antenna providing high-angle skywaveradiation at the lower end of the frequency range of operation andlow-angle skywave radiation at the upper frequencies.

There has been a long time need for antenna structures having theability to communicate with mobile stations such as ships and planes atvariable ranges from to approximately 1,000 miles. The needed antennastructures must have broad beams in azimuth (wider than a dipole beamwidth) and be preferably omnidirectional. In order that theirpropagation characteristics be optimum, the antenna structure must haveradiation patterns that in elevation launch waves at angles that arecompatible with the ionosphere for a given lineal range away from thetransmitter. A normal station using broad beam vertically polarizedantennas, such as a whip in its simplest form or a vertically polarizedlog periodic antenna, provides radiation generally restricted to thelower 45 in elevation with little or no ability for control of radiationpattern shape. Such antennas simply cannot provide satisfactory servicewith the high radiation angles characteristic of short rangecommunications. This is particularly so since these antennas must be fedagainst a ground plane or set of wires extending through a considerablearea obviously requiring a large installation area. There are otherproblems with such installations such as arise with antenna proximity toimperfectly conducting ground causing losses in the launching of theradiations. Furthermore, the vertically polarized waves radiated fromsuch antennas are particularly susceptible to distortion due to terrainobjects in the direction of propagation. The wave launching efficiencycurve is accentuated disadvantageously with the propensity of locationchoice with installations in typical military and other service sitesseeming many times to present combinations of the problems outlined.

Horizontal polarization in signal radiations is much more conducive tothe efficient launching of signal waves without having to rely oncritical ground systems and is such as to permit desired control ofelevation plane radiation pattern by virtue of allowing discretelocations of horizontal elements or substantially horizontal elements inheight above ground. Dipoles in an antenna structure comprising ahorizontal polarization design are individually directional, however,and thus quadrature sets of elements properly phased are required toproduce a broad beam. The inherent phasing of quadrature horizontalelements has a tendency to produce high angle circular polarization atsome frequency for a broad band antenna. For short range communications,however, this circular polarization is undesirable because, while intemperate latitudes a single characteristic wave in the ionosphere islaunched, the possibility exists of the antenna not functioning as areceptor of high angle waves by virtue of being cross polarized to theincoming waves. Thus, a short range communication requirement is topreclude circular polarization at high angles, and also to precludelinear polarization in order to mitigate against polarization fading.Thus, a design requirement that must be met is to provide a high angleradiator antenna structure that is always elliptically polarized.

A practical manifestation of a horizontally polarized omnidirectionalantenna using a single tower supporting structure is that at least theuppermost elements must be tilted down toward ground. Thus, designobjectives include the use of a single tower antenna supportingstructure with quadrature radiating elements that achieve ellipticalpolarization overhead, and with the elements arranged in a manner tosimultaneously tailor the elevation plane radiation patterns to aprescribed shape while maintaining the omnidirectionality withinprescribed limits. I

It is, therefore, a principal object of this invention to provide an HFbroadband omnidirectional antenna capable of providing substantiallygapless coverage in range from 0 to approximately 1,000 miles.

Another object is to provide such an antenna that is operational throughapproximately a frequency band of from 2 MHz to 30 MHz utilizingpredominantly horizontal polarization.

A further object is to attain optimized antenna signal propagationthrough high-angle skywave radiation at the lower end of the 2 MHz to 30MHz frequency range of operation and low-angle skywave radiation at theupper frequencies.

Still a further object is to provide an antenna array with the phasecenter approximately a quarterwavelength above ground at the lowerfrequencies increasing, with frequency increase from 2 MHz to 6 MHz, tonear a half-wavelength above ground.

Features of the invention useful in accomplishing the above objectsinclude, in a high frequency broadband orrmidirectional antenna, a logperiodic antenna operating through the 2 MHz to 30 MHz frequency rangeand providing gapless communication between 0 and 1,000 miles. This iswith two right angle vertical radiating element planes each containinglog periodic related radiating elements all supported in the overallantenna structure by guys anchored to and from a center singlefabricated triangularly cross sectioned tower mast and extended toground anchors. Further, the highest frequency shortest dipole elementsare adjacent the lower apex center end of the tower mast, and

then the radiating elements becoming progressively longer in logperiodic relation with successively higher elements in each of the tworight angle radiating element vertical planes. This is continuedserially successively through a series of single radiating element tobroader radiating elements composed of two spaced generally parallelwires with outer ends electrically interconnected, and ultimately, inone of the planes, a broad three wire radiating broadband element oneach side in that plane where the three wires of the opposite radiatingsides are of sufficient length and so spaced as to have effectively aninduced interconnect toward the outer ends without requiring actual wireinterconnect at the outer ends thereof. The feed for the antenna isthrough a coaxial unbalanced 50 ohm feedline transformed through a balunjumper lead connected to the two sides of a balanced 200 ohmcharacteristic impedance transmission line that extends verticallythrough the triangular cross sectioned vertical center mast. The 200 ohmbalanced transmission line is structurally supported within the antennamast with each of the two sides of the balanced 200 ohm balanced transmission line having three wires as an aid to attaining the desiredbalanced 200 ohm characteristic impedance. It

is important to note that as an additional feature of this highfrequency antenna that the feed from the 200 ohm balanced transmissionline is first from the two line sides directly to the lowest highestfrequency pair of radiating elements and then from the two line sides tothe next higher pair of radiating elements that are the lowest pair ofelements in the other vertical plane. Then the next successively higherfeed connections to a pair of elements in crossover feed from theopposite sides of the 200 ohm transmission line with this pair ofelements again in the original plane of radiating elements. This sametype crossover feed is used with the next successive higher radiatingpair of elements that happen to be in the other plane. These direct andcrossover feed system connections are continued with alternated pairs ofradiating elements from vertical plane to plane at right angles to eachother to in effect accomplish a spiral feed with the radiating elementpair feed connection locations being successively spaced atapproximately 90 phase angles up the balanced transmission line asrelated to the respective operational frequencies involved. Stated moresimply this is witheach of the radiating element planes containing a setof increasingly sloped single wire dipole elements and more highlylocated longer trapezoidal shaped multiwire radiating elements. Theelements of each plane are feed connection staggered on the transmissionline with respect to the three wire sides thereof so that at any onefeed location there is only one pair of elements attached to thetransmission line and these are in the same plane. This structureprovides an antenna giving gapless skywave coverage from to 1,000 milesover the HF band of 2-30 MI-Iz. Please note, however, that this is notto be interpreted to mean that the coverage from 0 to 1,000 miles can becovered with any single one or two frequencies. The range covereddepends on the propagation conditions (time of day and season of year),angle of maximum radiation above the horizon (take off angle) and thefrequency of transmission. The antenna radiation elements arepredominantly horizontally polarized and use the ground to form theradiation pattern that varies in take off angle from overhead to 30.Higher angle patterns are formed for the frequencies from 2 MHz toapproximately 6 MHz with this done to provide short range coverage offrequencies that do not penetrate the ionosphere at near perpendicularincidence. As the angle of incidence with the ionosphere is decreased(that is the take off angle is also decreased), the maximum frequency isincreased before the energy penetrates the ionosphere. This is preciselythe sort of action that the antenna gives during operation with take offangle getting lower as frequency is increased with it thereby beingadvantageously useful in attaining longer ranges with such frequencyincrease.

Specific embodiments representing what are presently regarded as thebest modes of carrying out the invention are illustrated in theaccompanying drawings.

In the drawings:

FIG. 1 represents an HF broadband omnidirectional antenna with a singleantenna mast;

FIG. 2, a partial schematic and antenna element feed system for theantenna;

FIG. 3, a perspective of the unbalanced coaxial line input to two linebalanced 200 ohm output balun with corrections from each of the balancedsides to respective three-line leads in the antenna structure;

FIGS. 4, 5, 6 and 7, respectively, partial detailed showings of two-wirebalanced line feed connections to respective radiation elements as seenlooking down thereon from lines 4-4, 5-5, 66 and 7-7, of FIG. 2respectively;

FIG. 8, a VSWR to frequency in MHz diagram for the antenna;

FIGS. 9 through 14, elevation voltage patterns for the antenna at 2 MHz,4 MHz, 6 MHz, 12 MHz, 20 MHz and 30 MHz respectively; and

FIGS. 15 through 20, azimuth voltage patterns through elevation beammaximum at 2 MHz, 4 MHz, 6 MHz, 12 MHz, 20 MHZ and 30 MHz respectively.

Referring to the drawings:

The horizontally polaiized, omnidirectional, log periodic array antenna30 of FIG. 1 is shown to be supported by a single galvanized steelfabricated tower mast 31 of triangular cross section at the antennacenter. The tower 31 is supported at its base by a concrete tower pad 32partially buried in the ground so as to adequately support the weight ofthe tower 31 and antenna 30 structure. The tower mast 31 is laterallysupported by four top guy wire or cable assemblies 33N, 33E, 33S and 33Wthat are individually fastened to the top of antenna mast tower 31 byfour individual guy insulating and fastening units 34. The guys 33N,33B, 338 and 33W extend from their upper end fastenings to the top ofthe tower mast 31 to connections with individual concrete anchor pads35N, 35E, 35S and 35W that are partially buried in soil so as toadequately support tension pull of the respective guys in their supportof the center tower mast 31 and radiating elements supported in theantenna structure 30. Four lower guys 36 are fastened at their upperends to the antenna mast 31 in the mid region up the antenna mast and attheir ground anchor ends in concrete anchor pads 37. This is with thelower guys 36 substantially equally spaced about the antenna mast andindividually located approximately midway in the four quadrants betweenthe north, east, south and west orientations of the 33N, 33E, 33S, and33W guys. Please note that the guy wire or cables 33N, 33E, 33S, and 33Wand the four guys 36 while generally made of conductive metal wirecable, are individually assembled of a plurality of conductive metallengths with interspersed insulators 38. The insulators are providedwith each guy cable assembly to break up electrically conductive lengthsin the guy assemblies and minimize any tendency to induced reactiveresonance thereof at any antenna operational frequency that wouldpossibly be harmful in the attainment of antenna signal propagationoperational objectives.

Four catenary wire rope assemblies 39N, 39E, 39S, and 39W are connectedat their upper ends by individual insulator connectors 40 to themid-regions of the top guys 33N, 33E, 33S, and 33W, respectively. Thecatenary wire rope assemblies 39N, 39E, 39S, and 39W extend from theirtop connections to connections with individual anchor rods 41 eitherright at or closely adjacent to tower mast mounting pad 32. Further,each of the catenary ropes 39N, 39E, 39S, and 39W is properly tensionedbetween the respective top and anchor connections to give proper outersupport to radiating elements connected at their outer ends thereto,respectively, as evidenced by the respective top guys 33N, 33E, 33S, and33W being drawn down at the respective catenary connections thereto.Further, the catenary metal wire rope assemblies 39N, 39E, 39S, and 39Ware provided with insulators 42 interrupting the electrical conductivityof each of the catenary ropes between the outer supporting connection ofthe rope with respective radiating elements of the antenna structure.Again, this is to minimize the chance of undesired resonant conditionsbeing induced in conductive metal lengths of the catenary ropes, andfurther to prevent any undesired cross signal conductive paths betweenthe outer ends of radiating elements.

The antenna radiating elements extend from outer end connections, viainsulator assemblies 43 with respective catenary wire ropes, inward toelectrical signal connection with a side of a two sided 44 and 45balanced 200 ohm signal feed transmission line extended verticallywithin the tower mast 31 from adjacent balun structure 46 as shown inFIG. 2. Referring also to FIG. 3, in addition to FIGS. 1 and 2, the feedfrom radio equipment (not shown) is provided to balun 46 through anunbalanced coax line 47. This is with balun 46 mounted on a mountingplate 48 above the bottom triangular mounting section 49 of antenna mast31 that includes a bottom triangular plate 50 resting directly on thetop of concrete tower mounting pad 32. A tautly tensioned structuralsupporting cable 51 is extended from an anchor connection with bottomplate 50 upward through the center of the triangularly crosssectionedantenna mast 31 to a top connection adjacent to the top of the towermast 31 in a conventional manner (detail not shown), and this is withthis top connection of cable 51 being above both the structural supportinterconnect and the electrical feed connections with the top radiatingelements of the antenna structure. In any event, the 50 ohm unbalancedimpedance of coaxial transmission line 47 is converted to a 200 ohmbalanced output through the balun structure 46 with the two outputsbeing passed through connective lines 52 and 53 to three-wire balancedtransmission line sides 44 and 45.

The three-wire sides 44 and 45 of two-sided balanced 200 ohmtransmission line are provided with a bottom anchor yoke structure 54having a cross member 55 anchored to the center structuralsupportingcable 51 and dual predominantly insulating material anchorconnector assemblies 56 and 57 for the respective three-wire sides 44and 45 of the balanced transmission line. Please note that there is anupper yoke assembly structure (not shown in detail) much the same as thelower yoke structure 54 to mount and support the twosided 44 and 45balanced transmission line from structural support cable 51 in the upperportion of the tower structure above feed connection to the top pair ofradiating elements in the antenna. The two opposite transmission lineupper and lower yoke assemblies 54 so mounted on the supporting cable 41within the tower mast 31 that the three-wire side 44 and 45 of thebalanced transmission line are tautly tensioned and supported in placeto avoid any undesired shorting contact with any structural element ofthe tower through the extremes of any environmental conditions to beencountered. This is with feed connections to respective pairs ofradiating elements of the antenna being supported in proper locationsalong the balanced transmission line.

The center structural supporting cable 51 mounts a plurality ofradiating element wire inner end mounting connective assemblies 58 witheach fixed in place on the cable 51 as by tight friction crimping fit ofa collar 59 on cable 51. Each structural assembly 58 is provided withtwo opposite side inward end pivotably mounted dielectric arms 60 thatare equipped with outer end feedline connective conductive clamps 61pivotably pinned 62 thereto. The clamps 61, of the structural connectiveassembly 58 shown in FIG. 3, anchor the inner ends of the lowestvertically positioned shortest length highest frequency dipole elements63E and 63W of the east-west oriented planar array. This is with clamps61 also acting as conductive clamps electrically connecting feed jumperlines 64E and 64W to radiating elements 63E and 63W, respectively, todirectly connect via the jumper feed lines 64E and 64W and conductiveclamps 65E and 65W on the three-wire sides 44 and 45, respectively, ofthe 200 ohms balanced transmission line.

Please note that the lower portion of the antenna tower mast 31appearing in FIG. 3 is turned around so as to better illustrate thebalun 46 structure mounting and electrical lines 52 and 53 interconnectto the two sides 44 and of the balanced transmission line in the towerstructure. This is with what is really an east radiating element 63Eappearing to the left and a west radiating element 63W shown extendingto the right in FIG. 3. With reference to the showing of FIG. 1 andparticularly to FIG. 2 with more normal north, east, south, and westorientation of radiation elements continuing vertically up the tower,the next radiation element structural interconnect and feed jumperconnection is via another duplicate interconnect assembly 58structurally mounting the inner ends of radiating elements 66N and 668as the highest frequency shortest radiating elements in the bottom ofthe north-south oriented vertical planar array. This is with attendantfeed jumper interconnect lines 67N and 678 similar to jumper feed lines64E and 64W with attendant duplicate interconnecting clamps 65 on thetransmission line three wire line sides 44 and 45 and clamps 61 of therespective pivoted opposite side arms 60 of the respective radiatingelement inner end mounting structure 58. The next pair of radiatingelements up the antenna structure are radiating elements 68E and 68Wagain in the east-west oriented vertical plane with inner ends supportedfrom structure supporting cable 51 by another element pair inner endinterconnect structural assembly 58. However, in this instance thejumper feed lines 69E and 69W are long crossover jumper lines toopposite sides 45 and 44, respectively, of the two sided 200 ohmbalanced transmission line. The next higher pair radiating elements inthe antenna are radiating elements 70N and 708 that also usetransmission line feed long crossover jumper lines 71N and 718 just aswith the jumper feed lines 69E and 69W for the next lower set ofradiating elements in the antenna structure. In like manner theremaining dipole radiating elements successively up the antenna have thesame order successively jumper line feed alternating to successive pairsbetween vertical planes with through repetitive sequences resulting in aspiral-like feed with the feed to successively higher elements beingvertically spaced approximately 90 in phase successively one fromanother up the antenna in the spiral like feed successively seriallyprovided therefor. Reference also to the vertical plane section FIGS. 4,5, 6 and 7 is helpful in understanding the spiral like phased feedarrangement serially up the antenna with respect to successively,respectively, the lowest radiating pair of elements 63E and 63W, thenext higher pair 66N and 66S, the next pair 68E and 68W, and the nexthigher pair 70N and 70S. The same phase spacing feeding relationshipexists with respect to the successively higher pairs of radiatingelements 72E and 72W, 74N and 74S, 76E and 76W, 78N and 78S, 80E and 80Wand 82N and 82S and the respective jumper feed lines 73E, 73W, 75N, 75S,77E, 77W, 79N, 79S, 81E, 81W, '83N, and 838 that alternate betweenvertical planes. However, it should be noted that the next successivelyhigher radiating elements are fatter two-wire radiating elements. Thisis with, for example, the next higher radiating element pair being aneast-west vertical plane oriented pair with the east broad radiatingelement 84E and west broad radiating element 84W each having a lowerwire 85L and an upper wire 85U in generally vertically spaced parallelrelation. The inner ends of wires SSL and wires 85U are respectivelyconnected to two likewise spaced radiating element inner end structuralmounting assemblies 58. Two long crossover jumper leads 86E and 87Econnect transmission line side 45 with the broad radiating element 84Elower and upper wires SSL and 85U interconnected at the outer endthereof by electrically conductive wire 88E, and two long crossoverjumper leads 86W and 87W connect transmission line side 44 with lowerand upper wires 85L and 85U interconnected at the outer end byelectrically conductive wire 88W. Obviously the radiating interconnectstructures 58 are balanced particularly with broad radiating element 84Whaving correspondingly identified elements as with the east broadradiating element 84E. The next higher radiating element pair hasopposite broad two wire radiating pair elements 89N and 895 in thenorth-south vertical plane with outer end wire interconnects 90N and 905with other components duplicating similar components mounting andfeeding the broad element pair 84E and 84W. The next higher radiatingelement pairs are successively in order alternating between planes thebroad element pairs 91E and 91W, 92N and 92S, and 93E and 93N, and thenthe next higher longest and lowest frequency range broad radiatingelement pair 94N and 948 are three-wire broad radiating elements in thenorth-south vertical plane. With this top radiating element pair thethree wires 95N, 96N, 97N and 95S, 96$

and 97S, respectively, are interconnected by three of It is ofsignificant interest to note that in order that a reasonably compactrelatively inexpensive single mast. 31 antenna 30 of rugged constructionbe provided radiating elements are sloped. at varying degrees of slopefrom the highest degree of slope at the topmost broad radiating elementpair 94N and 94S. Then down through the antenna the slope of radiatingelements is progressively lessened until at the lowermost shortest highfrequency radiating element dipole pairs there is little, if any, slopedownward from their respective center mast interconnect. The pivotalinner end interconnection mounting of dielectric material arms 60advantageously permits the respective interconnect as-' semblies 58 toreadily adjust to the required slope of the radiating element wire endsthey, respectively, interconnect.

The orthogonal antenna 31 with the antenna radiating elements making upa log periodic dipole array lying in two vertical orthogonal planesdepends upon ground reflection in developing the desired radiationpatterns. It is an antenna having VSWR to frequency in MHzcharacteristics from the 50 ohm unbalanced coaxial cable input linethrough the balun to 200 ohm balanced transmission line extendingvertically up within the antenna tower mast 31 such as shown in FIG. 8and not exceeding 2.5 to l at any place over the frequency range. Theantenna 30 with its horizontally polarized propagation characteristicsuses ground relection in forming the radiation patterns that vary intakeoff angle from overhead to 30 such as would be in accord theelevation plane radiation patterns shown for 2lvfl-Iz,4MI-Iz,6M1-lz,12M1-Iz,20MI-Iz,and30MHz in FIGS. 9 through 14, respectively. Further,with the horizontal component of radiating elements in the twoorthogonal planes and the spacing of the radiating elements on thefeedline so that phase between the planes is approximately results inomnidirectional azimuth patterns varied to some degree from patternsobtained with true circular polarization with, however, the deviationtherefrom being highly desired. If two antennas were truly circularlypolarized and were at both ends of a signal path there would beinstances where excessive transmission loss would occur with decouplingwhere the incident received wave would possess one sense of circularpolarization while the antenna would be receptive to the opposite sense.In any event it is of interest to refer to the azimuth planed radiationpatterns that are generally semielliptical with these azimuth planeradiation patterns shown for 2 MI-Iz,4M1-Iz,6lVII-Iz,12lVl1-Iz,20lVlI-Iz,and30lVfl-lzin FIGS. 15 through 20, respectively.Thus, it is particularly advantageous that the radiating elements arespaced on the transmission line feed system of the antenna so that thephase between planes is approximately 90 thereby resulting inomnidirectional azimuth patterns. This combined with the shift of thephase center of the antenna toward the apex of feed point as thefrequency is increased with, for example, the phase center being aboutone-fourth wavelength above ground at the lower frequencies with agradual change to one-half wavelength at higher frequencies is quiteuseful in providing high angle elevation patterns at low frequenciesthat shifts to approximately 30 at frequencies above 6 MHz.

Whereas this invention is herein illustrated and described with respectto a single specific embodiment thereof, it should be realized thatvarious changes may be made without departing from the essentialcontributions to the art made by the teachings hereof.

We claim:

ll. In an HF antenna operational through a substantial portion of a 2MHz to 30 MHz frequency range; a log-periodic dipole array with elementslying in orthogonal vertical planes with the apex approaching ground; asingle structural fabricated mast tower vertically mounted over a groundplane with the towerbase resting on a tower mounting pad at the ground;four equally spaced guy assemblies connected to an upper portion of thetower and extended to and tensioned to four individual outer guy anchormeans in the ground; four individual catenary rope assemblies oneconnected to each of said guy assemblies and connected to individualcatenary rope anchor means adjacent said tower mounting pad; signal feedmeans for said antenna including a vertically extended two sidedbalanced transmission line mounted by said tower mast; log periodicradiating elements mounted in pairs with inner ends mounted byindividual interconnect means at the tower center and extended to outerend connection with oppositely extended catenary rope assemblies; withsaid pairs of log periodic radiating elements being alternated betweenvertical orthogonal planes defined generally by said opposite guyassemblies and opposite catenary rope assemblies and the radiatingelements connected to the opposite pairs of catenary rope assemblies;and with feed connection from the two sides of said balancedtransmission line being a 180 phase related feed to the opposite sidesof each pair of radiating elements and with the feed spacing along saidbalanced transmission line of successively higher radiating elementpairs in the antenna being approximately a 90 phase shift successivelyresulting in a spiral feed up the antenna to successively higher andhigher element pairs in the antenna.

2. The HF antenna of claim 1, wherein the antenna radiation elements arepredominantly horizontally polarized and use the ground to form theradiation patterns that vary in take off angle from overhead highangleskywave radiation at the lower end of the 2 MHz to 30 MHz frequencyrange of operation to low-angle skywave radiation at the upperfrequencies.

3. The HF antenna of claim 2, wherein the log periodic radiatingelements are positioned by pairs with the highest frequency shortestradiating element pair the lowest element pair adjacent the antennalower apex ground end with the radiating element pairs progressivelybeing longer in their successive spacings higher and higher through theantenna to the lowest frequency longest radiating element pair as thetop radiating element pair in the antenna.

4. The HF antenna of claim 3, wherein the log periodic radiating elementpairs are proportioned and positioned to insure phase center shift fromapproximately a quarter-wavelength above ground at the lower frequenciesto a half-wavelength above ground with frequency increase fromapproximately 2 MHz to approximately 6 MHz.

5. The HF antenna of claim 4, wherein said log periodic radiatingelement pairs include a plurality of 10 said radiating element pairswith single wire radiating elements extended to outer end connectionwith insulating interconnect means at their outer ends mounted onrespective catenary rope assemblies.

6. The HF antenna of claim 5, wherein said log periodic radiatingelement pairs also include a plurality of broad radiating elements witha plurality of radiating element wires included in each broad radiatingelement; said broad radiating element pairs being larger lower frequencyradiating elements than the longest single wire radiating element; andwith said broad radiating element pairs positioned above the highestsingle wire radiating element in the antenna.

7. The HF antenna of claim 6, wherein the topmost pair of radiatingelements, as the longest, lowest frequency pair of radiating elements,are canted at a downward angle from their common interconnect at theantenna center to outer end connection with respective catenary ropeassemblies closely adjacent the connection of said catenary ropeassemblies with the respective guy assemblies; and with the catenaryrope assembly to guy assembly interconnect connections being at the midregion of the respective guy as semblies.

8. The HF antenna of claim 7, wherein the pairs of radiating elementsvary in the rate of downward canted angle from a maximum with thetopmost pair progressively less and less successively from radiatingelement pair to pair down the antenna to substantially horizontalradiating elements as the lowermost highest frequency radiating elementpair is approached.

9. The HF antenna of claim 6, wherein outer ends of radiating elementwires in individual units of a plurality of said broad radiatingelements are electrically interconnected by conductive material means.

10. The HF antenna of claim 9, wherein a plurality of said broadradiating elements are two wire elements having said conductive materialinterconnect at their outer ends.

1 1. The HF antenna of claim 6, wherein the plurality of radiatingelement wires in each side of at least one pair of said broad radiatingelements are sufficiently long and so spaced as to be so inductivelycoupled as to appear to have conductive material interconnect betweenelement wire ends in each respective side.

12. The HF antenna of claim 11, wherein the pair of broad radiatingelements having inductive interconnect between element wires in eachrespective side is the topmost pair of broad radiating elements in theantenna; and with each side having three inductively coupled elementwires.

13. The HF antenna of claim 7, wherein said individual interconnectmeans is in the form of an interconnect structure having a centerstructure fastened to a structural support member vertically extendedsubstantially along the vertical epicenter of the antenna, and oppositeside insulating material arms pivotally connected by individual sidepivot mount means to said interconnect means center structure; radiatingelement wire inner end fastening means mounted on the outer end of eachof said insulating material arms; and said individual fastening meanselectrically interconnecting jumper feed lines from respective sides ofsaid balanced transmission line and the inner ends of respectiveradiating wires structurally supported by said wire inner end fasteningmeans on the outer ends of said insulating material arms.

14. The HF antenna of claim 13, wherein the said structural supportmember is a support cable tautly vertically extended through the antennamast from a mast bottom plate through the position range of saidradiating elements from bottom to top to connection in the top portionof the antenna mast.

15. The HF antenna of claim 14, wherein each side of said balancedtransmission line is a three parallel wire side with conductiveelectrical interconnect through a feed jumper lead connective clamp inthe

1. In an HF antenna operational through a substantial portion of a 2 MHzto 30 MHz frequency range; a log-periodic dipole array with elementslying in orthogonal vertical planes with the apex approaching ground; asingle structural fabricated mast tower vertically mounted over a groundplane with the tower base resting on a tower mounting pad at the ground;four equally spaced guy assemblies connected to an upper portion of thetower and extended to and tensioned to four individual outer guy anchormeans in the ground; four individual catenary rope assemblies oneconnected to each of said guy assemblies and connected to individualcatenary rope anchor means adjacent said tower mounting pad; signal feedmeans for said antenna including a vertically extended two sidedbalanced transmission line mounted by said tower mast; log periodicradiating elements mounted in pairs with inner ends mounted byindividual interconnect means at the tower center and extended to outerend connection with oppositely extended catenary rope assemblies; withsaid pairs of log periodic radiating elements being alternated betweenvertical orthogonal planes defined generally by said opposite guyassemblies and opposite catenary rope assemblies and the radiatingelements connected to the opposite pairs of catenary rope assemblies;and with feed connection from the two sides of said balancedtransmission line being a 180* phase related feed to the opposite sidesof each pair of radiating elements and with the feed spacing along saidbalanced transmission line of successively higher radiating elementpairs in the antenna being approximately a 90* phase shift successivelyresulting in a spiral feed up the antenna to successively higher andhigher element pairs in the antenna.
 2. The HF antenna of claim 1,wherein the antenna radiation elements are predominantly horizontallypolarized and use the ground to form the radiation patterns that vary intake off angle from overhead high-angle skywave radiation at the lowerend of the 2 MHz to 30 MHz frequency range of operation to low-angleskywave radiation at the upper frequencies.
 3. The HF antenna of claim2, wherein the log periOdic radiating elements are positioned by pairswith the highest frequency shortest radiating element pair the lowestelement pair adjacent the antenna lower apex ground end with theradiating element pairs progressively being longer in their successivespacings higher and higher through the antenna to the lowest frequencylongest radiating element pair as the top radiating element pair in theantenna.
 4. The HF antenna of claim 3, wherein the log periodicradiating element pairs are proportioned and positioned to insure phasecenter shift from approximately a quarter-wavelength above ground at thelower frequencies to a half-wavelength above ground with frequencyincrease from approximately 2 MHz to approximately 6 MHz.
 5. The HFantenna of claim 4, wherein said log periodic radiating element pairsinclude a plurality of said radiating element pairs with single wireradiating elements extended to outer end connection with insulatinginterconnect means at their outer ends mounted on respective catenaryrope assemblies.
 6. The HF antenna of claim 5, wherein said log periodicradiating element pairs also include a plurality of broad radiatingelements with a plurality of radiating element wires included in eachbroad radiating element; said broad radiating element pairs being largerlower frequency radiating elements than the longest single wireradiating element; and with said broad radiating element pairspositioned above the highest single wire radiating element in theantenna.
 7. The HF antenna of claim 6, wherein the topmost pair ofradiating elements, as the longest, lowest frequency pair of radiatingelements, are canted at a downward angle from their common interconnectat the antenna center to outer end connection with respective catenaryrope assemblies closely adjacent the connection of said catenary ropeassemblies with the respective guy assemblies; and with the catenaryrope assembly to guy assembly interconnect connections being at the midregion of the respective guy assemblies.
 8. The HF antenna of claim 7,wherein the pairs of radiating elements vary in the rate of downwardcanted angle from a maximum with the topmost pair progressively less andless successively from radiating element pair to pair down the antennato substantially horizontal radiating elements as the lowermost highestfrequency radiating element pair is approached.
 9. The HF antenna ofclaim 6, wherein outer ends of radiating element wires in individualunits of a plurality of said broad radiating elements are electricallyinterconnected by conductive material means.
 10. The HF antenna of claim9, wherein a plurality of said broad radiating elements are two wireelements having said conductive material interconnect at their outerends.
 11. The HF antenna of claim 6, wherein the plurality of radiatingelement wires in each side of at least one pair of said broad radiatingelements are sufficiently long and so spaced as to be so inductivelycoupled as to appear to have conductive material interconnect betweenelement wire ends in each respective side.
 12. The HF antenna of claim11, wherein the pair of broad radiating elements having inductiveinterconnect between element wires in each respective side is thetopmost pair of broad radiating elements in the antenna; and with eachside having three inductively coupled element wires.
 13. The HF antennaof claim 7, wherein said individual interconnect means is in the form ofan interconnect structure having a center structure fastened to astructural support member vertically extended substantially along thevertical epicenter of the antenna, and opposite side insulating materialarms pivotally connected by individual side pivot mount means to saidinterconnect means center structure; radiating element wire inner endfastening means mounted on the outer end of each of said insulatingmaterial arms; and said individual fastening means electricallyinterconnecting jumper feed lines from respeCtive sides of said balancedtransmission line and the inner ends of respective radiating wiresstructurally supported by said wire inner end fastening means on theouter ends of said insulating material arms.
 14. The HF antenna of claim13, wherein the said structural support member is a support cable tautlyvertically extended through the antenna mast from a mast bottom platethrough the position range of said radiating elements from bottom to topto connection in the top portion of the antenna mast.
 15. The HF antennaof claim 14, wherein each side of said balanced transmission line is athree parallel wire side with conductive electrical interconnect througha feed jumper lead connective clamp in the transmission line toradiating element wire inner end jumper interconnect feed for allradiating elements up and down the antenna.
 16. The HF antenna of claim15, wherein said two three wire sides of the balanced transmission lineare supported in vertical spaced apart relation extended between anupper yoke assembly and a lower yoke assembly; and a balun fed by anunbalanced coaxial transmission line, and with the balun having abalanced two wire output electrically connected respectively to oppositesides of said balanced transmission line.